title: I-motif nanospheres: unusual self-assembly of long cytosine strands.
abstract: The synthesis and characterization of novel DNA structures based on tetraplex cytosine (C) arrangements, known as i-motifs or i-tetraplexes, is reported. Atomic force microscopy (AFM) investigation shows that long C-strands in mild acidic conditions form compact spherically shaped nanostructures. The DNA nanospheres are characterized by a typical uniform shape and narrow height distribution. Electrostatic force microscopy (EFM) measurements performed on the i-motif spheres clearly show their electrical polarizability. Further investigations by scanning tunneling microscopy (STM) at ultrahigh vacuum reveals that the structures exhibit an average voltage gap of 1.9 eV, which is narrower than the voltage gap previously measured for poly(dG)-poly(dC) molecules in similar conditions.
authors.affiliation: Department of Biochemistry George S. Wise Faculty of Life Sciences, Tel Aviv University Ramat Aviv 69978, Israel.
authors.forename: Dragoslav
authors.initials: D
authors.lastname: Zikich
authors.forename: Ke
authors.initials: K
authors.lastname: Liu
authors.forename: Lior
authors.initials: L
authors.lastname: Sagiv
authors.forename: Danny
authors.initials: D
authors.lastname: Porath
authors.forename: Alexander
authors.initials: A
authors.lastname: Kotlyar
mesh_terms: D003596:Cytosine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D016252:Microscopy, Scanning Tunneling; D054118:Nanospheres / Q000737:chemistry* / Q000648:ultrastructure; D009690:Nucleic Acid Conformation; D013057:Spectrum Analysis; D055672:Static Electricity
chemical_list: D003596:Cytosine